The latest pre-release build can usually be found
here.
Added for emphasis: Prerelease software should be expected to have bugs. The purpose of a public alpha/beta/RC process is to help identify bugs in a real-world context. Prerelease builds will contain experiments, tests, and lots of new code. If you come across a bug, please report it along with a recipe to reproduce.
Please post any comments and especially bug reports about pre-release builds in this forum. It's best to keep discussion of features and bugs in the main forums, and on outside forums, limited to the current release build, and talk about the new stuff here.
Pre-release and especially builds marked "alpha" or "test" can have unexpected behavior! In the worst case, projects saved with a prerelease build may not preserve all settings when opened in a non-prerelease build.
You can install the prerelease just like a regular release, overwriting the release version, or you may prefer to install to a separate location on disk, or even do a portable installation.